Consider your goals
Chances are, you probably have at least an idea of which college major and career you plan on pursuing after high school. Thus, the next thing to consider when deciding which IB courses to take at which level is whether or not a course subject is relevant to your college and career goals.
In general, you should always try to take courses related to your expected college major and career goals at HL rather than SL. For instance, if you plan on studying pre-med in college to prepare you for a career as a doctor, it would make sense to take HL biology, chemistry, and physics so that you learn as much as possible about the field you plan on pursuing.
Taking HL IB courses in areas relevant to your goals can pay off in another major way: Depending on the credit-transfer policy of the college you ultimately attend, you may be able to use high HL IB scores to earn college credit toward your degree. This may allow you to bypass lower-level and introductory college courses, saving you time and money when it comes to earning your degree.
Consider your ability
The bottom line when it comes to deciding at what level to take which IB course is this: Can I handle this course at HL? Taking a particularly challenging HL class may look great on write my essay cheap transcript, but only if you do well. Doing well in an SL IB course is better than doing poorly in an HL IB course.